[2] Combining features of ancient Roman and Byzantine buildings and other local traditions, Romanesque architecture is known by its massive quality, thick walls, round arches, sturdy pillars, barrel vaults, large towers and decorative arcading.

Although many have been extended and altered in different styles, a large number remain either substantially intact or sympathetically restored, demonstrating the form, character and decoration of Romanesque church architecture.

[26] Architecture of a Romanesque style also developed simultaneously in the north of Italy, parts of France and in the Iberian Peninsula in the 10th century and prior to the later influence of the Abbey of Cluny.

The most notable single building that demonstrates this is St Mark's Basilica, Venice, but there are many lesser-known examples, particularly in France, such as the church of Saint-Front, Périgueux and Angoulême Cathedral.

The continual movement of people, rulers, nobles, bishops, abbots, craftsmen and peasants, was an important factor in creating a homogeneity in building methods and a recognizable Romanesque style, despite regional differences.

This resulted in the building of castles at strategic points, many of them being constructed as strongholds of the Normans, descendants of the Vikings who invaded northern France under Rollo in 911.

[28][29][30] In Germany, the Holy Roman Emperors built a number of residences, fortified, but essentially palaces rather than castles, at strategic points and on trade routes.

However, the church of St. Sernin at Toulouse, 1080–1120, has remained intact and demonstrates the regularity of Romanesque design with its modular form, its massive appearance and the repetition of the simple arched window motif.

On each of the routes abbeys such as those at Moissac, Toulouse, Roncesvalles, Conques, Limoges and Burgos catered for the flow of people and grew wealthy from the passing trade.

[38] A common characteristic of Romanesque buildings, occurring both in churches and in the arcades that separate large interior spaces of castles, is the alternation of piers and columns.

There are many variations on this theme, most notably at Durham Cathedral where the mouldings and shafts of the piers are of exceptional richness and the huge masonry columns are deeply incised with geometric patterns.

[38] In Italy where open wooden roofs are common, and tie beams frequently occur in conjunction with vaults, the timbers have often been decorated as at San Miniato al Monte, Florence.

[3] Vaults of stone or brick took on several different forms and showed marked development during the period, evolving into the pointed ribbed arch characteristic of Gothic architecture.

[44] The diagonal ribs could also be depressed, a solution used on the sexpartite vaults at both the Saint-Étienne, (Abbaye-aux-Hommes) and Sainte-Trinité, (Abbaye-aux-Dames) at Caen, France, in the late 11th and early 12th centuries.

[50] Romanesque church façades, generally to the west end of the building, are usually symmetrical, have a large central portal made significant by its mouldings or porch, and an arrangement of arched-topped windows.

At San Miniato al Monte the definition of the architectural parts is made even clearer by the polychrome marble, a feature of many Italian Medieval façades, particularly in Tuscany.

At Santa Maria della Pieve, Arezzo, this screening is carried even further, as the roofline is horizontal and the arcading rises in many different levels while the colonettes that support them have a great diversity of decoration.

Polygonal towers were often used on crossings and occur in France, Germany, Italy and Spain such as that of the Old Cathedral, Salamanca, which is covered by a dome supported on a ribbed vault.

By the early 12th century composite piers had evolved, in which the attached shafts swept upward to a ribbed vault or were continued into the mouldings of the arcade, as at Vézelay Abbey, Saint-Étienne, Caen, and Peterborough Cathedral.

The apsidal east end was often a focus of decoration, with both architectonic forms such as arcading and pictorial features such as carved figures, murals and occasionally mosaics.

The arcades are often richly decorated and are home to some of the most fanciful carved capitals of the Romanesque period with those of Santo Domingo de Silos in Spain and the Abbey of St Pierre Moissac, being examples.

[41] In England, such decoration could be discrete, as at Hereford and Peterborough cathedrals, or have a sense of massive energy as at Durham where the diagonal ribs of the vaults are all outlined with chevrons, the mouldings of the nave arcade are carved with several layers of the same and the huge columns are deeply incised with a variety of geometric patterns creating an impression of directional movement.

In general, the style of ornament was more classical in Italy, such as that seen around the door of San Giusto in Lucca, and more "barbaric" in England, Germany and Scandinavia, such as that seen at Lincoln and Speyer Cathedrals.

(See picture above under "Vault") The long barrel vault of the nave provides an excellent surface for fresco, and is decorated with scenes of the Old Testament, showing the Creation, the Fall of Man and other stories including a lively depiction of Noah's Ark complete with a fearsome figurehead and numerous windows through with can be seen the Noah and his family on the upper deck, birds on the middle deck, while on the lower are the pairs of animals.

Adam represents a highly naturalistic and lively portrayal, while in the figure of Seth, the robes have been used to great decorative effect, similar to the best stone carving of the period.

[58] Abbot Suger's innovative choir of the Abbey of Saint-Denis, 1140–44, led to the adoption of the Gothic style by Paris and its surrounding area, but other parts of France were slower to take it up, and provincial churches continued to be built in the heavy manner and rubble stone of the Romanesque, even when the openings were treated with the fashionable pointed arch.

[38] In Italy, although many churches such as Florence Cathedral and Santa Maria Novella were built in the Gothic style, or utilising the pointed arch and window tracery, Romanesque features derived from the Roman architectural heritage, such as sturdy columns with capitals of a modified Corinthian form, continued to be used.

All over Europe, dwellers of the town and country built houses to live in, some of which, sturdily constructed in stone, have remained to this day with sufficient of their form and details intact to give a picture of the style of domestic architecture that was in fashion at the time.

Examples of all these types of buildings can be found scattered across Europe, sometimes as isolated survivals like the two merchants' houses on opposite sides of Steep Hill in Lincoln, England, and sometimes giving form to a whole medieval city like San Gimignano in Tuscany, Italy.

The type of modern buildings for which the Romanesque style was most frequently adapted was the warehouse, where a lack of large windows and an appearance of great strength and stability were desirable features.